Elevator employing radio frequency identification devices (rfids)

ABSTRACT

An elevator safety chain includes a plurality of passive radio frequency identification devices (RFIDs) ( 15 - 18, 22, 34 - 36  and  63 ), which are associated, respectively, with hoistway door locks, upper hoistway limits, lower hoistway limits, overspeed detection, car door lock, emergency stop switch, and inspection switch. RFlDs may be associated with car the call buttons ( 34 ) and/or hall call buttons ( 14, 19 ). The RFIDs may have a switch ( 43, 44 ) in the frequency-determining circuitry ( 40, 41 ) which defeats the RFID&#39;s ability to respond, or a switch ( 48 ) which alters the responding frequency. The RFIDs may sense safe or unsafe conditions, or call requests, by either the presence of absence, or vice versa, of adjacent magnetic reluctance ( 51, 62, 71 ).

TECHNICAL FIELD

This invention relates to an elevator safety chain in which the statusor condition of a monitored safety-related parameter of the elevator iscommunicated by wireless transmission from an interrogated, passiveRFID.

BACKGROUND ART

As is known, the safety chain of literally every elevator comprises aseries of switches, all of which must be made (closed) so that theentire safety chain is a closed, conductive circuit, otherwise, theelevator is prevented from operating. In the past, elevator safetychains comprised a plurality of discrete switches, each of which have amoveable contact which connects between a pair of circuits when aparameter is in a safe condition, and which disconnects from at leastone circuit in the safety chain when the parameter is no longer in asafe condition. Examples of switches in the safety chain are hoistwaydoor lock switches, elevator door switch, emergency stop switch,inspection switch on the top of a cab, upper and lower hoistway limitswitches, and the overspeed switch. The various switches areinterconnected by wiring, which in turn must conform to local governmentregulation codes with respect to size and location of wires andconduits. Furthermore, once a building is wired to provide a safetychain, it is difficult to alter the building configuration, or thearchitectural design of the landings, due to the imbedded wiring. Theelevator and hoistway door lock switches must be mounted on the doorsthemselves, and therefore are connected by flexible wiring either to thecab or to the building, as the case may be.

To overcome the foregoing and other deficiencies in hard-wired, discreteswitch safety chains, a wireless safety chain for elevator systems isdisclosed in U.S. patent application Ser. No. 09/899,400, filed Jul. 5,2001. Therein, each parameter related to elevator safety has a sensorrelated to a wireless communication means, such as transceivers, so thatwhen the monitored parameter becomes unsafe, the condition of the sensorcauses the transceiver to be switched off. A master transceiver relatedto the elevator controller sends a token to a first transceiver, whichin turn will send it to the next transceiver, and so forth. It will notbe sent through all of the wireless communication means of the safetychain and back to the master transceiver whenever any parameter is in anunsafe condition; thus, the controller will be informed that an unsafecondition exists. Power for the transceivers may be supplied by hardwireto the building power, by passive battery, or by a battery system whichis recharged by inductive coupling, such as with a recharging circuitdisposed on the elevator car. Use of hardwired power obviates theadvantage of a wireless system, in that wires supplied for power are asinconvenient as wires interconnecting the safety chain switches. Batteryoperation requires far too much maintenance, cost and environmentalimpact. Inductively coupled recharging systems are complex andunreliable.

The foregoing analysis is applicable as well to call buttons, in the carand at the landings.

DISCLOSURE OF INVENTION

Objects of the invention include a safety chain: having components whichrely on neither hardwired power nor batteries; which are passive; inwhich sensing of the unsafe condition may be integral with the relatedtransceiver; providing improved flexibility, low cost, low maintenance,and ease of upgrading at low cost. Other objects include provision of:improved communication of elevator service calls; integrated wirelesstransmission of elevator service calls; and simplified, passivecommunication of elevator service calls.

According to the present invention, transceivers related to variousconditions monitored by an elevator safety chain and related to callbuttons are passive, comprising, for instance, radio frequencyidentification devices (RFIDs). According further to the invention, aswitch which becomes open upon the existence of an unsafe elevatorcondition may be connected directly with, or incorporated into therelated passive transceiver. In further accord with the invention, thesensing of an unsafe condition may be an integral part of the passivetransceiver; an example is the use of adjacent structural parts of theelevator (such as a door component) to either tune or detune thefrequency determining circuit of the passive transceiver so as tocommunicate the safe or unsafe s condition of the corresponding elevatorparameter.

As is well known, the RFID is powered by the received electromagneticenergy, and may respond only to a signal of its own unique frequency, orto a signal on a common frequency which however has an address codeunique to the individual RFID. The RFID will then respond bytransmitting a signal which may contain its address and which, in thiscase, will contain the condition of the related parameter, in the safetychain or a call button. If an address is not appropriate, the frequencyof the RFID will identify the source of the response.

Other objects, features and advantages of the present invention willbecome more apparent in the light of the following detailed descriptionof exemplary embodiments thereof, as illustrated in the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified, front elevation schematic of an elevatorhoistway and machine room incorporating the invention.

FIG. 2 is a simplified, front elevation schematic of an elevator carincorporating the present invention.

FIGS. 3-7 are simplified schematic illustrations of passive transceivertuning circuits with which the invention may be practiced.

FIG. 8 is a partial side elevation view of a hoistway door lock,illustrating how a passive transmitter of the present invention maybecome tuned when adjacent to a safety-related structural element.

FIG. 9 is a simplified, partial side elevation view of the elevatorlimits, illustrating how passive transceivers of the invention maybecome detuned when adjacent to a safety-related structural element.

MODE(s) FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, a hoistway 11 of an elevator system includes aplurality of hoistway doors 12, 13, there being one set 12, 13 for eachlanding. Each set has a passive transmitter 15, such as an RFID,associated with the corresponding hoistway door lock. The condition ofthe door lock is part of the safety chain; if any of the hoistway doorsare not locked, the elevator safety chain will fail. Each landing alsohas an up hall call button with a related transceiver 14 or a down hallcall button with a related transceiver 19, or both. The hoistway alsohas disposed therein a plurality of transceivers 16 related to upperlimit switches and a plurality of transceivers 17, 18 related to lowerlimit switches. In this example, within the machine room 20 of theelevator system, elevator overspeed detection will have a correspondingpassive transmitter 22. A transceiver 23 is in,wired communication withthe elevator car controller 24, and communicates with other transceiversand passive transmitters in the elevator system. For instance, atransceiver 26 may interrogate the condition of the hoistway doors forthe three lowest floors by sending out signals either on a uniquefrequency or with a unique address code so as to successivelyinterrogate the status of each related door lock as reflected by thecorresponding one of the passive transmitters 15. Similarly, thetransceiver 26 may interrogate the passive transmitters 17, 18 relatedto the lower limit switches. A transceiver 27 may interrogate thepassive transmitters 15 related to the hoistway door locks of the upperthree floors, and may interrogate the passive transmitters 16 to provideindications of the condition of the upper limits. The transceiver 23will then receive communications from the transceivers 26, 27 indicativeof the various passive transmitter responses in the hoistway. Thetransceiver 23 may also interrogate the passive transmitter 22 todetermine the condition of the related overspeed sensor. Depending uponthe number of floors in the building, additional transceivers such astransceivers 26, 27 may be provided so as to be within range of all ofthe transceivers 15 in the hoistway.

In FIG. 2, an elevator car 30 has a pair of doors 30, 32 and an RFID 33related to the car door lock switch. The elevator car 30 also has aplurality of car call buttons with related RFIDs 34, and an emergencystop switch with a related RFID 35. As is known, there is also aninspection switch on the top of the cab, and in this case, an RFID 36related thereto. The RFIDs 33-36 will be interrogated by any of thetransceivers 23, 26, 27. There are other conditions in the elevatorwhich are monitored within the safety chain, which are not shown hereinfor clarity.

The RFIDs may be arranged so as to reflect the condition of asafety-related parameter of the elevator, in a variety of ways. Thesimplest are shown in FIGS. 3 and 4 where the frequency-determining RFloop containing a capacitor 40 and an inductor 41 is either opened by aswitch 43 (FIG. 3) or shorted by a switch 44 (FIG. 4). Either of thesearrangements will cause the RFID to provide no response at all. On theother hand, the RFIDs can be caused to produce two different responses,one indicative of a safe condition and the other indicative of an unsafecondition, as is illustrated in FIG. 5. Therein, an additional capacitor47 is in series with the switch 48, the two being in parallel with thecapacitor 40 and the inductor 41. When the condition is safe, thecapacitor 47 is in the circuit, causing the RFID to be responsive at afirst frequency. But if the condition becomes unsafe, the switch 48 willbecome open and the capacitor 47 will no longer be in the circuit; then,the RFID will respond at a different frequency indicative of the unsafecondition. Utilizing a dual response of this type will allow thecontroller to identify the particular RFID which has sensed an unsafecondition, in contrast with the prior art, serial-switch safety chainwhich provided no indication of which of the switches has become openand thus no indication of the nature of the failure. In the embodimentsof FIGS. 3-5, the switch must be disposed to react to the conditionbeing monitored, and the RFID should be located immediately adjacentthereto, the switch and wiring being accommodated in thefrequency-determining loop.

An alternative form of response is illustrated in FIG. 7. Therein, thecapacitor 40 and inductor 41 may indicate one condition when the RFID isadjacent to a structure 51 having magnetic reluctance as indicated inFIG. 6, but will have a different frequency when there is no adjacentmagnetic reluctance, as illustrated in FIG. 7. This may be utilizedeither to sense the presence of magnetic reluctance 51 as being the safecondition, or to sense the presence of the magnetic reluctance 51 asbeing the unsafe condition. The first of these is illustrated withrespect to a hoistway door switch, a portion of which is shown in FIG.8. Therein, the lock selvage 53 (the locking lip) is fastened to theheader 54 of the doorway. The locking member 55 is disposed on ahoistway door 56. When a lip 59 engages selvage 53 as seen in FIG. 8, acontact portion 62 (which normally makes a connection between twoterminals on the hoistway door lock switch to indicate that the doorlock is engaged) will be adjacent to an associated RFID 63 so as toprovide tuning of the frequency-determining loop, as illustrated in FIG.6, so as to provide a response indicative of safety. However, if theportion 62 is not immediately adjacent the RFID 63, the situation willbe as in FIG. 7 and the response will either be non-existent, orindicative of an unsafe condition.

The opposite situation may be obtained as illustrated in FIG. 9.Therein, the lower limit switches 17, 18 are shown as disposed on aframe 66 which is mounted to the rail 67 by brackets 68. The well-knowncam 71 is disposed by brackets 72 to the stile 74, 15 which comprisesthe main vertical frame of the elevator platform, as is known. As can beseen, when the elevator gets close to the bottom of the hoistway, thecam 71 will be adjacent to the switch 17, causing it to detune thefrequency-determining circuitry, as is illustrated in FIG. 6, and eithercausing there to be no response from the RFID 17 or, depending upon theprotocol being used, a response indicative of the unsafe condition.Obviously, as the elevator goes lower in the hoistway, the cam 71 willbecome adjacent to additional ones of the RFIDs 18, thus providing theindication of the successive unsafe conditions due to the position ofthe elevator car in the hoistway. Thus, alteration of thefrequency-determining circuit by means of magnetic reluctance can eitherbe utilized so the presence of the reluctance indicates a safe condition(FIG. 8) or an unsafe condition (FIG. 9).

The call buttons may each have a passenger-actuated button switchincorporated into the RFIDs frequency determining circuitry (FIGS. 3-5),or they may each have a passenger-displaced member with reluctance(FIGS. 6 and 7). In systems having button lights to indicate when a callis registered, the lights will normally be wired to building power; theRFID may connect the power through a solid state switch in response to acall confirmation signal transmitted to the RFID. The interrogationsshould be at a repetition frequency, such as 5 HZ or 10 HZ, sufficientto coincide with button actuation, which may be as short as 200 msec to500 msec.

1. An elevator safety chain for monitoring the condition of a pluralityof safety-related parameters of an elevator, said parameters includingat least one of: hoistway door lock, car door lock, upper limits, lowerlimits, emergency stop switch, inspection switch, and overspeed sensor;characterized by: at least one transceiver (23, 26, 27) for transmittinginterrogation signals and for receiving responses to said interrogationsignals; and at least one passive radio frequency identification device(22, 33, 35, 36) (RFID) associated with a corresponding one of saidparameters, the frequency determining circuitry (40, 41, 43, 44, 47, 48)of any said RFID being related to said corresponding parameter to havethe capability to provide a transmitted response to an interrogationsignal from one said transceiver indicative of a safe condition, whenthe condition of the corresponding parameter is safe, and not providingsaid indication of a safe condition when the condition of thecorresponding parameter is not safe.
 2. A safety chain according toclaim 1 wherein: said RFID includes a switch (44, 48) that is opened andclosed in response to the condition of the corresponding parameter, saidswitch associated with frequency-determining circuitry (40, 41) of saidRFID so as to cause the frequency determination to result in atransmitted response indicative of a safe condition when said switch isin a position indicative of the fact that the condition of thecorresponding parameter is safe.
 3. A safety chain according to claim 2wherein said switch (43, 48) is connected in series withfrequency-determining elements (40, 41, 47) of said frequencydetermining circuitry.
 4. A safety chain according to claim 2 whereinsaid switch (44) is connected in parallel with frequency-determiningelements (40, 41) of said frequency determining circuitry.
 5. A safetychain according to claim 2 further comprising: an additionalfrequency-determining element (47); and wherein said switch (48)connects said additional frequency-determining element to saidfrequency-determining circuitry.
 6. An elevator safety chain accordingto claim 1 wherein: said frequency-determining circuitry (40, 41) isresponsive to structure having magnetic reluctance adjacent to saidRFID; and further comprising: a structure (51, 71) having magneticreluctance, the position of which is indicative of the condition of saidcorresponding parameter, the safe or unsafe condition of said parameterbeing determined by the presence or absence of said structureimmediately adjacent to said RFID in a manner which will alter thefrequency of said frequency-determining circuit.
 7. A safety chainaccording to claim 6 wherein the presence of said structure (71)adjacent to said RFID (17) indicates a safe condition.
 8. A safety chainaccording to claim 6 wherein the presence of said structure (71) havingmagnetic reluctance adjacent to said RFID (18) indicates an unsafecondition.
 9. An elevator call system for monitoring at least one of acar call button and a hall call button, characterized by: at least onetransceiver (23, 26, 27) for transmitting interrogation signals and forreceiving responses to said interrogation signals; and at least onepassive radio frequency identification device (RFID) (14, 19, 34)associated with a corresponding one of said call buttons, the frequencydetermining circuitry (40, 41, 43, 44, 47, 48) of any said RFID beingrelated to said corresponding call button to have the capability toprovide a transmitted response to an interrogation signal from one saidtransceiver indicative of the button being actuated, when thecorresponding button is actuated and not providing said indication ofthe button being actuated when the corresponding button is not actuated.10. A safety chain according to claim 9 wherein: said RFID includes aswitch (44, 48) that is operated by the corresponding button, saidswitch associated with frequency-determining circuitry (40, 41, 47) ofsaid RFID so as to cause the frequency determination to result in atransmitted response indicative of a call request when said switch is ina position indicative of the fact that the corresponding button isactuated.
 11. A safety chain according to claim 10 wherein said switch(43, 48) is connected in series with frequency-determining elements (40,41, 47) of said frequency determining circuitry.
 12. A safety chainaccording to claim 10 wherein said switch (44) is connected in parallelwith frequency-determining elements (40, 41) of said frequencydetermining circuitry.
 13. A safety chain according to claim 10 furthercomprising: an additional frequency-determining element (47); andwherein said switch (48) connects said additional frequency-determiningelement to said frequency-determining circuitry (40, 41).
 14. Anelevator safety chain according to claim 9 wherein: saidfrequency-determining circuitry is responsive to structure havingmagnetic reluctance adjacent to said RFID; and further comprising: astructure having magnetic reluctance, the position of which isdetermined by said corresponding button, the actuated or unactuatedcondition of said button being indicated by the presence or absence ofsaid structure immediately adjacent to said RFID in a manner which willalter the frequency of said frequency-determining circuit.
 15. A safetychain according to claim 6 wherein the presence of said structureadjacent to said RFID indicates a call request.
 16. An elevator systemincluding a safety chain for monitoring the condition of a plurality ofsafety-related parameters of an elevator, said parameters including atleast one of: hoistway door lock, car door lock, upper limits, lowerlimits, emergency stop switch, inspection switch, and overspeed sensor;said elevator system also for monitoring at least one of a car callbutton and a hall call button, characterized by: at least onetransceiver (23, 26, 27) for transmitting interrogation signals and forreceiving responses to said interrogation signals; at least one passiveradio frequency identification device (safety RFID) (22, 33, 35, 36)associated with a corresponding one of said parameters, the frequencydetermining circuitry (40, 41, 43, 44, 47, 48) of any said safety RFIDbeing related to said corresponding parameter to have the capability toprovide a transmitted response to an interrogation signal from one saidtransceiver indicative of a safe condition, when the condition of thecorresponding parameter is safe, and not providing said indication of asafe condition when the condition of the corresponding parameter is notsafe; and at least one passive radio frequency identification device(call RFID) (14, 19, 34) associated with a corresponding one of saidcall buttons, the frequency determining circuitry of any said call RFIDbeing related to said corresponding call button to have the capabilityto provide a transmitted response to an interrogation signal from onesaid transceiver indicative of the button being actuated, when thecorresponding button is actuated, and not providing said indication ofthe button being actuated when the corresponding button is not actuated.